googleapis/mcp-toolbox · error

failed to unmarshal job JSON: %w

Error message

failed to unmarshal job JSON: %w

What it means

GetJob unmarshals the protojson-produced bytes into map[string]any. This error means json.Unmarshal failed on bytes that protojson just produced — practically indicates the JSON bytes are invalid, which points to a corrupted marshal step or memory/exotic edge case rather than user input.

Source

Thrown at internal/sources/dataproc/dataproc.go:410

	req := &dataprocpb.GetJobRequest{
		ProjectId: s.Project,
		Region:    s.Region,
		JobId:     jobId,
	}

	jobPb, err := client.GetJob(ctx, req)
	if err != nil {
		return nil, fmt.Errorf("failed to get job: %w", err)
	}

	jsonBytes, err := protojson.Marshal(jobPb)
	if err != nil {
		return nil, fmt.Errorf("failed to marshal job to JSON: %w", err)
	}

	var result map[string]any
	if err := json.Unmarshal(jsonBytes, &result); err != nil {
		return nil, fmt.Errorf("failed to unmarshal job JSON: %w", err)
	}

	consoleUrl := JobConsoleURLFromProto(jobPb, s.Region)
	logsUrl, err := JobLogsURLFromProto(jobPb, s.Region)
	if err != nil {
		return nil, fmt.Errorf("error generating logs url: %v", err)
	}

	wrappedResult := map[string]any{
		"consoleUrl": consoleUrl,
		"logsUrl":    logsUrl,
		"job":        result,
	}

	return wrappedResult, nil
}

View on GitHub (pinned to 8cc6e09de2)

Solutions

1. Log jsonBytes on failure to inspect what protojson produced
2. Verify the standard encoding/json package is in use (no shadowed imports/build tags)
3. Rebuild the project cleanly (go clean && go build) to rule out stale artifacts

job, err := svc.GetJob(ctx, jobId)
if err != nil && strings.Contains(err.Error(), "unmarshal job JSON") {
	// rebuild cleanly and retry; log jsonBytes if reproducible
}

When it happens

Trigger: json.Unmarshal(jsonBytes, &result) failing after protojson.Marshal succeeded — an internal inconsistency, essentially unreachable in normal operation.

Common situations: Effectively only seen with custom builds, instrumented JSON libraries, or vendoring anomalies.

Understand the failure class

Background: "failed to unmarshal" / json.Unmarshal errors: why parsing a response into a Go struct fails and how to fix it — this error's family across 23 libraries.

Related errors

• operation finished with error but could not marshal error ob
• failed to unmarshal cluster JSON: %w
• failed to marshal job to JSON: %w
• failed to marshal result: %w
• failed to unmarshal operation bytes: %w

AI-assisted analysis of googleapis/mcp-toolbox@8cc6e09de2 (2026-09-05). Data as JSON: /api/errors/97f187c1fa1003fc. Report an issue: GitHub.